1. Field of the Invention
This invention relates to seat belt systems and more particularly to seat belt systems using a retractor which is winding up two seat belts on a single retractor shaft one over the other.
2. Prior Art
In conventional seat belt systems in which two restraining belts are wound up on a single retractor shaft one over the other, when only one belt (i.e., the shoulder restraining belt) is pulled out, the remaining lap restraining belt is extended in the same manner. However, since no pulling force is applied to the lap restraining belt, this belt sometimes becomes slack inside the retractor mechanism (as indicated by the broken line A in FIG. 1). When a restraining belt becomes slack inside the retractor case mechanism, there is a danger that this slackened restraining belt will become stuck between the retractor shaft and the case of the retractor mechanism so that extension becomes impossible. Furthermore, there is a danger that this slackened restraining belt will interfere with the operation of the emergency locking retractor mechanism. In addition to these drawbacks, there is the further drawback that if the passenger is not careful while using the system, slack of the restraining belt will sometimes be generated so that it is not sufficient to restrain the passenger and this restraining condition is extremely dangerous.
This invention has been designed to eliminate these conventional technological defects.